KR20220090549A - Method of increasing cell stability of polyethylene resin - Google Patents

Abstract

A method of increasing the cell stability of a required high molecular weight bimodal high density polyethylene resin, the melt storage modulus G'(G" of the resin by performing oxygen tailoring of the resin on the required high molecular weight bimodal high density polyethylene resin) = 3000 Pascal) and independently increasing both the complex viscosity ratio SH1000 to produce an oxygen-tailored high molecular weight bimodal high density polyethylene resin having a target increase in cell stability. It uses a tailoring effective amount of molecular oxygen (O ₂ ) to achieve bubble stability while using the above advanced rheological properties of dynamic mechanical spectroscopy, but analyzing the data in other ways that are more sensitive to changes in resin composition and properties. Achieving a balance sheet with a target increase of

Description

Method of increasing cell stability of polyethylene resin

Polyethylene polymers and related methods and articles.

Publications and patents in the field or related thereto are disclosed in U.S. Patent Nos. 5,739,266; 5,962,598; 5,998,558; US Patent Application Publication No. 2004/0236041 A1; 2005/0012235 A1; 2006/0038315 A1; and 2011/0178262 A1.

Thin films can be used in a variety of applications, such as packaging and medical care.

Almost all polyethylene films are produced as cast films or blown films. Cast films are produced by the film casting process on a film casting machine and blown films are produced by the film blowing process on a film blowing machine.

Film blowing machines typically have an extruder consisting of a circular die for extruding the film into an annular shape, the circular die also defining a central gas port for blowing an internal gas flow within the annular extruded film. The film blowing machine also includes a guide device and a set of pinch rollers and the film blowing process performs annular extrusion vertically upward through the guide device with a set of pinch rollers.

In general, the film blowing process involves melting a polyethylene resin in an extruder, annularly extruding the polyethylene melt through a circular die, annularly extruded with an internal gas flow (e.g., air) blown inward through a central port. expanding the polyethylene, followed by cooling the resulting blown bubble, and collapsing the cooled bubble to provide a blown film. The pinch roller collapses the air bubble and causes it to wind on the roller. The wound film may then be split, gusseted and/or surface treated in a downstream line operation.

Polyethylene polymer resins can be used in melt-blowing film extrusion processes to produce thin films if the resin has bubble stability, also known as downgauging capability. Bubble stability herein means that the melt can be blown up until its thickness decreases to 10 micrometers (μm) or less without experiencing any blown film bubble instability. These instabilities include draw resonance (varying bubble diameter, also called hour-glassing), helical instability (“Mae Westing”, “snaking” or hula-hooping). (wobbly bubbles, also called Hula Hooping), slow or rapid bubble breathing (the expansion of the blown film delays or exceeds the desired rate of expansion), sagging (heavy bubbles or sleeping) Settling bubbles, also called air bubbles), tearing (the resin stops stretching and tears off the die lip, also known as snap off), blow holing (random holes in the film), and fluttering ) (shaking or trembling below the frost line, where the frost line is the height above the circular die at which the polyethylene melt solidifies).

Neubauer et al. (US 2011/0178262 A1) control the cell stability of high molecular weight bimodal high density polyethylene resins by oxygen tailoring the melt of the resin to change the relaxation spectral index (RSI) values. Neubauer's method is the melt elasticity (ratio of melt storage modulus (G') to loss modulus (G") measured at a dynamic frequency equal to 0.1 (G'/G" at 0.1 radians/second (rad/s))) is more sensitive than controlling the bubble stability using Occasionally, large changes in the RSI value may be necessary to achieve the target foam stability. For example, Neubauer's Inventive Example 1 required an increase of at least about 140% in the initial RSI value in order for the resin to reach a regime with "good" cell stability (Neubauer copied herein to Figure 1) see Fig. 2).

The present inventors have found that high molecular weight bimodal high density polyethylene (HDPE) resins (“virgin resins”) obtained in polymerization reactors generally do not have cell stability. To increase cell stability, the melt of the resin may be contacted with O ₂ prior to oxygen tailoring, eg, annular extrusion of the resin in a film blowing process. This oxygen tailoring can be performed in the extruder of a film blowing machine.

We found that too little oxygen tailoring will result in bubble instability at thin film gauges (eg ≤ 10 μm) during blown film fabrication. Such blown film bubble instability may include any one or more of the aforementioned draw resonance(s), helical instability, slow or rapid bubble breathing, sagging, tearing, blow hauling (rupture) and fluttering.

Too much oxygen tailoring will result in poor blown film impact and poor tear performance as measured by dart drop impact and Elmendorf tear methods, respectively. This poor mechanical performance includes a dart drop impact of 250 grams (g) or less (e.g., less than 225 g or less than 200 g), a machine direction (MD) Elmendorf tear of 20 g or less (e.g. < 19 g). , and a transverse direction (CD) Elmendorf tear of 30 g or less (eg < 29 g).

The present inventors have recognized that conventional methods of controlling the oxygen tailoring of high molecular weight bimodal HDPE resins to increase cell stability are not always sufficiently sensitive when the composition and thus properties of the resin change. The composition and properties of high molecular weight bimodal HDPE resins change when the resin is prepared in a polymerization reactor, such as a gas phase polymerization reactor, that is subjected to fluctuating reactor conditions. Fluctuating reactor conditions include reactor swings, changes to the residence time of the polymer in the reactor, transitions between different resin grades made in the reactor, and combinations thereof. Reactor swing includes oscillations or fluctuations in bed temperature, catalyst feed rate, catalyst activity, catalyst composition (eg, conversion between different catalysts), ethylene or comonomer feed rate, molecular hydrogen feed rate, or combinations thereof. do. Conversions between different resin grades include conversions between comonomers (eg, from making poly(ethylene- co -1-butene) copolymers to making poly(ethylene- co -1-hexene) copolymers, or vice versa). and preparing resins using the same comonomer but different density, molecular weight or melt index, or different comonomer content or distribution.

We found that the cell stability (in other words, cell instability) of certain high molecular weight bimodal HDPE resins is sensitive to the combination of the resin's melt storage modulus G' (at G" = 3000 Pascals) and the complex viscosity ratio SH1000. The inventors have found that resins with insufficient values for both of these advanced rheological properties also have unsatisfactory cell stability. Melt storage modulus G' (at G" = 3000 Pascals) and complex viscosity ratio of these resins. A method has been found to improve the SH1000 to increase the cell stability to a satisfactory or superior level.

The present inventors have found a way to increase the cell stability of high molecular weight bimodal high density polyethylene resins in need thereof (“needful bimodal HDPE resins”). The properties of the required bimodal HDPE resin are different from those of the previous resins prepared in the same reactor due to changes in reactor conditions, and therefore the oxygen tailoring conditions used to increase the cell stability of the previous resins are different from those of the required bimodal HDPE resins. It may not be effective to increase stability. That is, previous oxygen tailoring conditions may provide either too little oxygen tailoring or too much oxygen tailoring of the bimodal HDPE resin required. Therefore, there is a need for a sensitive method to determine the oxygen tailoring conditions for the required bimodal HDPE resin. This method is sensitive enough. The method performs oxygen tailoring of a determined amount of the resin based on the resin's melt storage modulus G' (at G" = 3000 Pascals) and the complex viscosity ratio SH1000 for the required bimodal HDPE resin to have a target increase in cell stability. It comprises preparing oxygen-tailored high molecular weight bimodal high density polyethylene resin.This method uses a tailoring effective amount of molecular oxygen (O ₂ ) to achieve the desired oxygen tailoring.This method uses dynamic mechanical spectroscopy (DMS) Using the above advanced rheological properties of , but analyzing the data in other ways that are more sensitive to changes in resin composition and properties, achieve the HDPE resin regime with the target increase in cell stability.

1 is a copy of the prior art FIG. 2 of Neubauer (US 2011/0178262 A1).
Figure 2 shows the oxygen tailoring results of a comparative method using melt elasticity (G'/G" at 0.1 rad/s) versus complex viscosity ratio SH1000 for oxygen-tailoring bimodal HDPE resins.
3 shows the oxygen tailoring results of the inventive melt storage modulus G' (at G" = 3000 Pascals) versus the complex viscosity ratio SH1000 for inventive oxygen-tailored bimodal HDPE resins 1B, 1C, 2B, 2C and 3C. , and comparisons with comparative oxygen-tailored bimodal HDPE resins 1A, 2A, 3A, 3B, 4A and 4B.

A method of increasing the cell stability of a high molecular weight bimodal high density polyethylene resin in need thereof ("needful bimodal HDPE resin"). The properties of the required bimodal HDPE resin are different from those of the previous resins prepared in the same reactor due to changes in reactor conditions, and therefore the oxygen tailoring conditions used to increase the cell stability of the previous resins are different from those of the required bimodal HDPE resins. It may not be effective to increase stability. That is, previous oxygen tailoring conditions may provide either too little oxygen tailoring or too much oxygen tailoring of the bimodal HDPE resin required. Therefore, there is a need for a sensitive method to determine the oxygen tailoring conditions for the required bimodal HDPE resin. This method is sensitive enough. The method performs oxygen tailoring of a determined amount of the resin based on the resin's melt storage modulus G' (at G" = 3000 Pascals) and the complex viscosity ratio SH1000 for the required bimodal HDPE resin to have a target increase in cell stability. It comprises preparing oxygen-tailored high molecular weight bimodal high density polyethylene resin.This method uses a tailoring effective amount of molecular oxygen (O ₂ ) to achieve the desired oxygen tailoring.This method uses dynamic mechanical spectroscopy (DMS) Using the above advanced rheological properties of , but analyzing the data in other ways that are more sensitive to changes in resin composition and properties, achieve the HDPE resin regime with the target increase in cell stability.

Additional inventive aspects follow; Some are numbered for easy cross-reference.

Aspect 1. A higher molecular weight (HMW) polyethylene polymer component and a lower molecular weight (LMW) polyethylene polymer component comprising an overall density of 0.935 to 0.970 grams/cubic centimeter (g/cm ³ ) and 200,000 to 450,000 grams/mole A method of increasing the cell stability of a required bimodal high density polyethylene (HDPE) resin having an overall weight average molecular weight (M _w ) of (g/mol), wherein the required bimodal HDPE resin is not prepared due to changes in reactor conditions. The properties of the modal HDPE resin are different from those of the previous resin made in the same reactor and the required bimodal HDPE resin has a first melt storage modulus G' (loss modulus G) of less than 1501 Pascals (eg, 1,0000.0 to 1500.0 Pascals). ″=at 3000 Pascals) and a first complex viscosity ratio (shear thinning) SH1000 of 33.0 to 49.0, which requires increased cell stability, the method being the required bimodal HDPE under oxygen-tailoring conditions. contacting the melt of the resin with an oxygen-tailoring mixture consisting essentially of a tailoring effective amount of molecular oxygen gas (O ₂ ) and one or more inert gases, wherein during said contacting the melt has a second melt storage of 1565 to 1900 Pascals at a temperature of 235° C. to 251° C. to produce an oxygen-tailored bimodal HDPE resin having a modulus G′ (at G″ = 3000 Pascals) and a second complex viscosity ratio SH1000 of 38.0 to 50.0; D792-13, method B; the M _w is determined according to the gel permeation chromatography (GPC) test method; the respective melt storage modulus G' (at G″ = 3000 Pascals) is determined by the melt storage modulus test measured according to the method; wherein each of the complex viscosity ratios SH1000 is equal to Eta*0.10/Eta*100, where Eta*0.10 is 0.10 is the complex viscosity in Pascal-seconds (Pa-s) measured in radians/second (rad/s) and Eta*100 is the complex viscosity in Pa-s measured at 100 rad/s, both of which are dynamic mechanical A method, measured according to an analytical test method. In aspect 1, the determined amount of oxygen tailoring of the bimodal HDPE resin required is based on the molecular weight distribution of the resin.

Aspect 2. The method of aspect 1, wherein the tailoring effective amount of O ₂ gas in the contacting step is as described by any one of limitations (i) to (ii): (i) X volume % of the oxygen-tailoring mixture ( O ₂ gas concentration in vol%); and (ii) the amount of O ₂ gas is parts by weight Y (ppmw) per million parts by weight of bimodal HDPE resin required.

Aspect 3. The oxygen-tailoring mixture of any of aspects 1 or 2, wherein the oxygen-tailoring mixture has an O ₂ gas concentration of X volume % (vol %), and wherein the oxygen-tailoring conditions meet any of limitations (i) to (iv). A method comprising: (i) the melt is at a temperature between 235°C and 245°C; (ii) the melt is at a temperature between 236° C. and 241° C.; (iii) the at least one inert gas of the oxygen-tailoring mixture is molecular nitrogen (N ₂ ), argon, helium, CO ₂ , one or more alkane(s), or a combination of any two or more thereof; and (iv) both (i) and (ii) and (iii).

Aspect 4. The method of any of aspects 1 to 3, wherein the oxygen-tailored bimodal HDPE resin has any one of limitations (i) to (iii): (i) a second melt storage modulus G' (at G″ = 3000) is 1565 to 1800 Pascals; (ii) the second complex viscosity ratio SH1000 is 40 to 49.4; (iii) both (i) and (ii).

Aspect 5. The method of any of aspects 1-4, wherein the oxygen-tailored bimodal HDPE resin passes the MLS350 cell stability test determined according to the Cell Stability Test Method.

Aspect 6. A method according to any of aspects 1 to 5, wherein the required bimodal HDPE resin has any one of limitations (i) to (vi): (i) the overall density is from 0.940 to 0.960 g/cm ³ lim; (ii) the total Mw is between 250,000 and 400,000 g/mol; (iii) the first melt storage modulus G' (at G" = 3000 Pascals) is 1001 to 1300 Pascals; (iv) the first complex viscosity ratio SH1000 is 35.0 to 48.0; (v) 8.0 to 10.0 grams/10 minutes an overall high load melt index (HLMI or I _21.6 ) of (g/10 min), and (vi) an overall melt flow ratio of 25 to 45, alternatively 30.1 to 39.4, alternatively 31.0 to 36.0, 5 (MFR5 or I _21.6 /I _5.0 ) - where I _21.6 is measured according to ASTM D1238-13 using the condition of 190°C/21.6 kilograms (kg); I _5.0 is ASTM D1238-13 using the condition of 190°C/5.0 kg Measured according to -.

Aspect 7. The method according to any of aspects 1 to 6, further comprising the following preliminary steps (A) and (B) prior to the contacting step: (A) determining the molecular weight distribution of the required bimodal HDPE resin. wherein the molecular weight distribution is (a1) the ratio of the weight average molecular weight of the HMW polyethylene polymer component to the weight average molecular weight of the LMW polyethylene polymer component (M _w-HMW /M _w-LMW ); (B) determining the effective tailoring amount of molecular oxygen gas (O ₂ ) effective in the contacting step as a function of the determined molecular weight distribution of the required bimodal HDPE resin.

Aspect 8. A method according to aspect 7, wherein the required bimodal HDPE resin has any of the limitations (i) to (iii): (i) the molecular weight distribution is (a1) M _w-HMW /M _w-LMW ratio, wherein M _w-HMW /M _w-LMW is 23 to 45; (ii) the molecular weight distribution is (a2) the ratio of the number average molecular weight of the HMW polyethylene polymer component to the number average molecular weight of the LMW polyethylene polymer component (M _n-HMW /M _n-LMW ), where M _n-HMW /M _n-LMW is 18 to 30; (iii) the molecular weight distribution is (a3) the ratio of the z-average molecular weight of the HMW polyethylene polymer component to the z-average molecular weight of the LMW polyethylene polymer component (M _z-HMW /M _z-LMW ), where M _z-HMW /M _z-LMW is 18 to 45, wherein M _w , M _n and M _z are determined according to a gel permeation chromatography (GPC) test method.

Aspect 9. An oxygen-tailored bimodal HDPE resin prepared by the method of any one of aspects 1-8. The oxygen-tailored bimodal HDPE resin has a second melt storage modulus G′ (at G″=3000) and a second complex viscosity ratio SH1000 described herein.

Aspect 10. A blown film comprising the oxygen-tailored bimodal HDPE resin of aspect 9. The blown film passes the MLS350 bubble stability test.

Aspect 11. A higher molecular weight (HMW) polyethylene polymer component and a lower molecular weight (LMW) polyethylene polymer component comprising an overall density of 0.935 to 0.970 grams/cubic centimeter (g/cm ³ ) and 200,000 to 450,000 grams/mole A method for determining whether a bimodal high density polyethylene (HDPE) resin having an overall weight average molecular weight (M _w ) of (g/mol) requires increased cell stability, comprising the required melt storage modulus G of the bimodal HDPE resin measuring the '(loss modulus G″ at 3000 Pascals) and the complex viscosity ratio (shear thinning) SH1000, and the bimodal HDPE has a melt storage modulus G' (at loss modulus G″=3000 Pascals) less than 1501 Pascals ( determining that increased cell stability is required when the complex viscosity ratio (shear thinning) SH1000 is between 33.0 and 49.0, eg, from 1,0000.0 to 1500.0 Pascals. In some embodiments, the method further comprises a preliminary step of determining, prior to the measuring step, whether the bimodal HDPE has been compositionally changed from the immediately preceding resin prepared in the same gas phase polymerization reactor.

The required bimodal HDPE resin comprises a higher molecular weight (HMW) polyethylene component and a lower molecular weight (LMW) polyethylene component. The required bimodal HDPE resin may have an overall density of 0.935 to 0.970 grams/cubic centimeter (g/cm ³ ) and an overall weight average molecular weight (M _w ) of 200,000 to 450,000 grams/mole (g/mol). The required bimodal HDPE resin will have a melt storage modulus G' (loss modulus G" at 3000 Pascals) of less than 1501 Pascals (eg, 1,0000.0 to 1500.0 Pascals) and a complex viscosity ratio (shear thinning) SH1000 of 33.0 to 49.0 Both G' (loss factor G" at 3000 Pascals) and SH1000 of the required bimodal HDPE resin are too low for adequate cell stability.

The required bimodal HDPE resin can be "compositionally changed" from the immediately preceding resin produced in the same gas phase polymerization reactor. The expression “compositionally-changed” means at least 1% (%), alternatively 1% to 10%, alternatively 1% in any one, two or more of the following resin properties. to 5%, alternatively from 5% to 10%: density, weight average molecular weight (M _w ), Log (MW) of the LMW polyethylene component, Log (MW) of the HMW polyethylene component, HMW and Amount of HMW polyethylene component based on total weight of LMW polyethylene component, high load melt index (I _21.6 ), melt flow ratio-5 (I _21.6 /I _5.0 ) - where density is ASTM D792-13, Method B measured according to; M _w is determined according to the gel permeation chromatography (GPC) test method; I _21.6 is measured according to ASTM D1238-13 using conditions of 190° C./21.6 kilograms (kg); I _5.0 is measured according to ASTM D1238-13 using the condition of 190°C/5.0 kg -.

To increase cell stability, the required melt of bimodal HDPE resin is oxygen tailored using a tailoring effective amount of molecular oxygen (O ₂ ). We found that the combination of G' (loss factor G″ at 3000 Pascals) and SH1000 properties is more sensitive to determining the tailoring effective amount of O ₂ than the RSI value or melt elasticity (G′/G″ at 0.1 rad/s). found that

The expression "tailoring effective amount" includes a higher molecular weight (HMW) polyethylene polymer component and a lower molecular weight (LMW) polyethylene polymer component under oxygen tailoring conditions and has a melting point of less than 1501 Pascals (eg, 1,0000.0 to 1500.0 Pascals). The required bimodal high density polyethylene (necessary bimodal HDPE) polymer having a storage modulus G' (at loss modulus G″ = 3000 Pascals) and a complex viscosity ratio (shear thinning) SH1000 of less than 49.5 (e.g., 33.0 to 49.0) ( For example, the required bimodal high density polyethylene (HDPE) resin) has a higher melt storage modulus G' (at G″ = 3000 Pascals) (e.g. 1565 to 1900 Pascals) and a higher complex viscosity ratio SH1000 (e.g. For example, 38.0 to 50.0) means any amount of molecular oxygen (O ₂ ) sufficient to convert to an oxygen-tailored bimodal high density HDPE polymer having increased cell stability.

The method may further comprise a preliminary step (prior to the oxygen tailoring step) of adjusting or correcting the tailoring effective amount to achieve an increase in a desired or desired amount of bubble stability under the specific set of circumstances. The adjustment or calibration may be based on any one or more of the following specific circumstances: (a) specific oxygen tailoring conditions (eg, the required temperature of the bimodal HDPE polymer, the O ₂ concentration in the oxygen tailoring mixture, and/or or the flow rate of the oxygen tailored mixture for the required bimodal HDPE polymer), (b) the amount of oxygen tailored required bimodal HDPE polymer, (c) the melt storage modulus G' of the oxygen tailored required bimodal HDPE polymer (loss modulus G ″ = at 3000 Pascals) and specific values of the complex viscosity ratio (shear thinning) SH1000, (d) molecular weight distribution between the HMW polyethylene component and the LMW polyethylene component of the required bimodal HDPE polymer, (e) under a known set of gas phase polymerization conditions. The residence time of the bimodal HDPE polymer required during production in the gas phase polymerization reactor, and (f) the specific configuration (size and shape) of the vessel (eg melt mixer or extruder apparatus) in which oxygen tailoring is performed. The resulting adjusted or corrected tailoring effective amount can be expressed in percent O ₂ by volume in the oxygen tailoring mixture, or in parts per million by weight (ppmw) of O ₂ relative to 1,000,000 parts by weight of the required bimodal HDPE polymer.

In some embodiments the adjustment or calibration is based on the molecular weight distribution between the HMW polyethylene component and the LMW polyethylene component. The expression "molecular weight distribution" of the required bimodal HDPE resin is the ratio of the weight average molecular weight of the HMW polyethylene polymer component to the weight average molecular weight of the LMW polyethylene polymer component (M _w-HMW /M _w-LMW ). This aspect of adjustment or calibration comprises determining the molecular weight distribution of a bimodal HDPE polymer in need of increased cell stability, wherein the molecular weight distribution is the weight average molecular weight of the HMW polyethylene polymer component to the weight average molecular weight of the LMW polyethylene polymer component. is the ratio of (M _w-HMW /M _w-LMW ); and determining a tailoring effective amount of O ₂ in an oxygen tailoring mixture consisting essentially of a tailoring effective amount of O ₂ and at least one inert gas, wherein the tailoring effective amount of O ₂ is an oxygen-tailoring having increased (and satisfactory) bubble stability. sufficient to make the used bimodal HDPE resin. For example, the tailoring effective amount of O ₂ gas can be determined as the volume % (X) of O ₂ gas in the oxygen-tailoring mixture based on 100 volume % of the oxygen-tailoring mixture and the total amount of oxygen-tailoring mixture used. wherein the total concentration of at least one inert gas is equal to 100-X, and X is determined from the molecular weight distribution according to the following equation (1): X vol% = 0.235 * (M _w-HMW /M _w-LMW ) + (0.041 * W) - 64.9% by volume (Equation 1), where each * represents a multiplication, + represents addition, - represents subtraction, and W represents the second melt storage achieved in the oxygen tailoring step. The target value for the modulus G' (at G″ = 3000 Pascals), where the target value W is between 1565 and 1900 Pascals.

Equation (1) above can be adapted for use with other oxygen tailoring equipment/work scales. For example, the calibration can be further adjusted for use in other instrument settings according to equation (1a): A*X vol% = 0.235 * (Mw-HMW/Mw-LMW) + (0.041 * W) ― 64.9 ( Equation 1a), where X, W, +, - and * are as defined above for Equation 1, and A is the instrument calibration factor. All other things being equal, the value of the equipment correction factor A increases as the size of the equipment and the amount of resin increase.

In some embodiments the effective amount of O ₂ gas used in the contacting step may be described as any one of limitations (i) to (iii): (i) the oxygen-tailoring mixture contains X volume % (vol %) O ₂ having a gas concentration, wherein X is 5 to 12% by volume of the oxygen-tailoring mixture, and the total concentration of the one or more inert gases is 95 to 88% by volume of the oxygen-tailoring mixture, respectively; (ii) the amount of O ₂ gas used in the oxygen tailoring step is parts by weight Y (ppmw) per million parts by weight of the compositionally changed bimodal HDPE resin, where Y is 20 to 200 ppmw; and (iii) both (i) and (ii). In some embodiments the contacting step is described by constraint (i), which is for entry of external atmosphere (eg, air) into the vessel or leakage of vessel atmosphere (eg, N ₂ ) out of the vessel. Knowing the volume percent of O ₂ gas that is used and added to the vessel when the contacting step is performed in an imperfectly sealed vessel (eg, an extruder) can more sensitively control the oxygen tailoring step. In another aspect the contacting step is described by constraint (ii), which is used when the contacting step is performed in a substantially sealed vessel (eg, an extruder) to oxygen tailor the weight of the compositionally modified bimodal HDPE resin. Knowing the ppmw of O ₂ gas added into the vessel for

In some embodiments, the oxygen-tailoring mixture may have an O ₂ gas concentration of X volume percent (vol %), and the oxygen-tailoring conditions may include any one of limitations (i)-(vi). : (i) the effective concentration X of the O ₂ gas is 6 to 11% by volume of the oxygen tailoring mixture and the total concentration of the one or more inert gases is 94 to 89% by volume of the oxygen-tailoring mixture, respectively; (ii) the effective concentration X of the O ₂ gas is between 6.5 and 10.4 volume percent of the oxygen tailoring mixture and the total concentration of the one or more inert gases is each between 93.5 and 89.6 volume percent of the oxygen-tailoring mixture; (iii) the effective concentration X of the O ₂ gas is between 9.0 and 11.0 volume percent of the oxygen tailoring mixture and the total concentration of the one or more inert gases is each between 91.0 and 89.0 volume percent of the oxygen-tailoring mixture; (iv) the melt is at a temperature of 235°C to 245°C; (v) the melt is at a temperature of 236° C. to 241° C. (eg, 239° C. to 241° C.); (vi) the at least one inert gas of the oxygen-tailoring mixture is molecular nitrogen (N ₂ ), argon, helium, CO ₂ , one or more alkane(s), or a combination of any two or more thereof. In some embodiments the oxygen tailoring condition comprises a combination of any two or more of the above limitations according to any one of (vii)-(x): (vii) any one of (i)-(iii) and (iv) both; (viii) any one of (i) to (iii) and (v) both; (ix) both (i) to (iii) and (vi); and (x) any one of (iv) and (v) and (vi), and any one of (i)-(iii).

The method is based on the molecular weight distribution of the resin to independently increase both the resin's melt storage modulus G' (at G″ = 3000 Pascals) and the complex viscosity ratio SH1000 to achieve the desired increase in cell stability of the required bimodal HDPE resin. and the amount of oxygen tailoring of the bimodal HDPE resin required. Each increase in the melt storage modulus G' (at G" = 3000 Pascals) can be no more than 50%, alternatively no more than 46%, and each increase in the complex viscosity ratio SH1000 can be no more than 18%, alternatively no more than 14.9% .

One skilled in the art of oxygen tailoring will appreciate the desired or desired increased cell stability and/or desired or desired melt storage modulus G' (at loss modulus G″ = 3000 Pascals) and complex viscosity of the bimodal HDPE polymer required in certain circumstances. The tailoring effective amount can be easily adjusted or calibrated to achieve a non (shear thinning) SH1000. For example, a suboptimal tailoring effective amount may be used initially in the oxygen tailoring step, after which the tailoring effective amount is determined by the melt storage modulus G' (at loss modulus G″ = 3000 Pascals) and complex of the bimodal HDPE polymer required under certain circumstances. Viscosity ratio (shear thinning) can be increased steadily (eg, continuously or stepwise) until the desired effect on SH1000 is achieved.

In any of the above aspects, the oxygen-tailored bimodal HDPE resin can have any of the limitations (i) to (iii): (i) 1585 to 1730 Pascals, alternatively 1620 to 1700 Pascals. a second melt storage modulus G' (at G" = 3000 Pascals), (ii) a second complex viscosity ratio SH1000 of 44.0 to 50.0, alternatively 46.0 to 49.0.

The melt storage modulus G' (at G" = 3000 Pascals), complex viscosity ratio SH1000, and melt elasticity (G'/G" at 0.1 rad/s) mentioned herein are measured for the entire bimodal HDPE resin, HMW It is not about the polyethylene polymer component or the LMW polyethylene polymer component. This is later shown in the data table marked as "All".

Oxygen tailoring, as used herein, refers to the process of contacting the required bimodal HDPE resin, typically in molten form, with molecular oxygen gas (O ₂ ). Embodiments of the method may contact the melt of the resin with pure O ₂ gas (100% by volume of O ₂ ), however, typically for safety reasons, embodiments of the method require the necessary bimodal HDPE resin to be mixed with O ₂ gas and one Contacted with an oxygen tailoring mixture consisting essentially of the above inert gas. The contacting step may be performed concurrently with the required thermomechanical treatment of the bimodal HDPE resin in the extruder to provide an oxygen-tailored bimodal HDPE resin that is also thermomechanically treated. Alternatively, the contacting step may be performed prior to the thermomechanical treatment step to provide an oxygen-tailored bimodal HDPE resin, and then the oxygen-tailored bimodal HDPE resin may be thermomechanically treated in an extruder to also thermomechanically A treated oxygen-tailored bimodal HDPE resin can be provided. A thermomechanical treatment step may be used to incorporate one or more additives into the desired bimodal HDPE resin and/or oxygen-tailored bimodal HDPE resin.

The extruder may be any extruder; For example, the extruder may be a single screw extruder or a multi screw extruder, such as a twin screw extruder or a continuous mixer. Such extruders are generally known to the person skilled in the art. The extruder is 0.10 to 0.50 kilowatt hours per kilogram (kWh) of polyethylene resin, alternatively 0.10 to 0.24 kWh per kilogram, alternatively 0.12 to 0.30 kWh per kilogram, alternatively 0.14 to 0.40 kWh per kilogram, alternatively 0.16 to 0.50 kWh per kilogram It can provide non-mechanical energy in the kWh range.

The contacting step (oxygen tailoring step) is such that the second melt storage modulus G′ (at G″=3000) is at least 10% greater than the first melt storage modulus G′ (at G″=3000), alternatively from 15% to 50% greater, alternatively 25% to 46% greater, alternatively 33% to 44% greater; or the second complex viscosity ratio SH1000 is at least 4% greater, alternatively 5% to 18% greater, alternatively 10% to 14.9% greater, alternatively 11.0% to 14.5 greater than the first complex viscosity ratio SH1000 % until greater; or until both.

Oxygen-tailored bimodal HDPE resins with or without additives may be pelletized by feeding a melt of oxygen-tailored bimodal HDPE resin from an extruder to a pelleter such as an underwater pelleter. The pelletizing step can be used to prepare the oxygen-tailored bimodal HDPE resin in pellet form.

Oxygen-tailored bimodal HDPE resin is an oxygen-tailored higher molecular weight (HMW) poly(ethylene-1-alkene) copolymer component and an oxygen-tailored lower molecular weight (LMW) poly(ethylene-1-alkene) an overall density comprising the copolymer constituents of 0.935 to 0.970 g/cm ³ , alternatively 0.940 to 0.960 g/cm ³ , alternatively 0.945 to 0.955 g/cm ³ , alternatively 0.948 to 0.951 g/cm ³ . may be an oxygen-tailored bimodal poly(ethylene-1-alkene) copolymer with The oxygen-tailored bimodal poly(ethylene-1-alkene) copolymer may be an oxygen-tailored bimodal poly(ethylene-1-butene) copolymer or alternatively an oxygen-tailored bimodal poly(ethylene-1-hexene) copolymer. ) copolymer, alternatively an oxygen-tailored bimodal poly(ethylene-1-butene) copolymer. The oxygen-tailored LMW poly(ethylene-1-alkene) copolymer component may have a M _w of 13,000 to 32,000 g/mol. The oxygen-tailored HMW poly(ethylene-1-butene) copolymer component may have a M _w from 450,000 to 750,000 g/mol.

The oxygen tailored bimodal HDPE resin may be free of any post-reactor added additives. The oxygen-tailored bimodal HDPE resin may contain one or more additives used during the production of the bimodal HDPE resin required in the polymerization reactor. For example, embodiments of oxygen-tailored bimodal HDPE resins may optionally contain deactivated polymerization catalysts, chain transfer agents, static control agents, or continuity additives. Chain transfer agents are well known and may be alkyl metals such as diethyl zinc. The static control agent or continuity additive may be aluminum stearate or polyethyleneimine.

Optionally, in the post oxygen tailoring process, the oxygen-tailored bimodal HDPE resin is melted (eg in an extruder) and zero, one or more additives, such as acid neutralizers (eg, hydrotalcite or metal deactivator), at least one antioxidant, a polyethylene polymer different in composition from the oxygen-tailored bimodal HDPE resin, a polypropylene polymer, a slip agent (e.g., erucamide, stearamide, or behenamide), ultraviolet light ( It can be combined with flame retardants and stabilizers (e.g. hindered amine stabilizers (HAS) such as hindered amine light stabilizers (HALS)) to stabilize oxygen-tailored resins against the effects of UV) light. Bimodal HDPE resins may also contain nucleating agents such as calcium or magnesium salts of 1,2-cyclohexanedicarboxylate.

The required bimodal HDPE resin contains a higher molecular weight (HMW) poly(ethylene-1-alkene) copolymer component and a lower molecular weight (LMW) poly(ethylene-1-alkene) copolymer component and contains 0.935 to 0.970 g bimodal poly(ethylene-1-alkene) having an overall density of /cm ³ , alternatively from 0.940 to 0.960 g/cm ³ , alternatively from 0.945 to 0.955 g/cm ³ , alternatively from 0.948 to 0.951 g/cm ³ . ) may be a copolymer. The bimodal poly(ethylene-1-alkene) copolymer is a bimodal poly(ethylene-1-butene) copolymer or alternatively a bimodal poly(ethylene-1-hexene) copolymer, alternatively a bimodal poly(ethylene -1-butene) copolymer. The LMW poly(ethylene-1-alkene) copolymer component may have a M _w of 13,000 to 32,000 g/mol. The HMW poly(ethylene-1-butene) copolymer component may have an M _w of from 450,000 to 750,000 g/mol.

The required bimodal HDPE resin used in the contacting step may be a virgin bimodal HDPE resin obtained from the polymerization reactor. That is, the virgin bimodal HDPE resin may be free of any post-reactor added additives. The virgin bimodal HDPE resin may contain one or more additives used during manufacturing in the polymerization reactor. For example, embodiments of virgin bimodal HDPE resins produced in gas phase polymerization reactors, such as ebullated bed gas phase polymerization reactors, may optionally contain a deactivated polymerization catalyst, chain transfer agent, static control agent or continuity additive. Chain transfer agents are well known and may be alkyl metals such as diethyl zinc. The static control agent or continuity additive may be aluminum stearate or polyethyleneimine.

Virgin bimodal HDPE resin is obtained by contacting ethylene and 1-alkene in a floating-bed gas phase polymerization reactor having a bed temperature of 90° C. to 100° C., ethylene (C ₂ ), 1-alkene (C _x ), molecular hydrogen gas (H ₂ ) ) and the induction condensing agent isopentane. The molar ratio of 1-alkene to ethylene in the reactor (C _x /C ₂ molar ratio) may be 0.003 to 0.03. In some embodiments, the C _x /C ₂ molar ratio may be slightly different for different 1-alkenes. For example, when 1-alkene is 1-hexene, the C _x /C ₂ molar ratio (C ₆ /C ₂ molar ratio) may be 0.003 to 0.015. When 1-alkene is 1-butene, the C _x /C ₂ molar ratio (C ₄ /C ₂ molar ratio) is from 0.006 to 0,030, alternatively from 0.010 to 0.020, alternatively from 0.011 to 0.015, for example 0.012 or 0.013 can be The molar ratio of molecular hydrogen gas to ethylene in the reactor (H ₂ /C ₂ molar ratio) can be from 0.001 to 0.01, alternatively from 0.0020 to 0.0050, alternatively from 0.0044 to 0.0021, such as 0.0040, 0.0034, or 0.0025. The residence time of the copolymer in the reactor may be from 2 to 5 hours, alternatively from 3 to 4.4 hours, alternatively from 3.4 to 4.1 hours, such as 3.6 hours, 3.8 hours, 3.9 hours, or 4.0 hours. Isopentane may be 5 to 15 mol% (mol%) based on the total gas in the reactor.

Optionally, in a post-reactor process, the virgin required bimodal HDPE resin is melted (eg in an extruder) and zero, one or more additives such as acid neutralizers (eg hydrotalcite or metal deactivators) ), at least one antioxidant, polyethylene polymers, polypropylene polymers, slip agents (e.g. erucamide, stearamide, or behenamide) that differ in composition from the required bimodal HDPE resin, to the effect of ultraviolet (UV) light. It can be combined with flame retardants and stabilizers (eg hindered amine stabilizers (HAS) such as hindered amine light stabilizers (HALS)) to stabilize the resin against It may contain nucleating agents such as calcium or magnesium salts of dicarboxylates.

film. Manufactured articles limited to one dimension.

high density. Applied to polyethylene having a density of at least 0.935 g/cm ³ , alternatively between 0.940 and 0.970 g/cm ³ measured according to ASTM D792-08 (Method B, 2-propanol). The HMW PE component and the LMW PE component may independently be high density polyethylene (HDPE).

homopolymer. A polymer derived from one species of monomer. Species can be real (eg, ethylene or 1-alkene), implicit (eg, as in poly(ethylene terephthalate)), or hypothetical (eg, as in poly(vinyl alcohol)). have.

Internal bubble cooling, or IBC, is a form of film blowing performed actively using auxiliary special purpose IBC equipment, such as that of US Patent Application Publication 2002/0150648 A1 to R. E. Cree.

The relative terms “higher” and “lower” in the HMW PE component and the LMW PE component are used in reference to each other and simply the weight average molecular weight of the HMW PE component (M _w-HMW ) is the weight average molecular weight of the LMW PE component (M _{w -LMW} ), ie M _w-HMW > M _w-LMW .

Any compound, composition, agent, mixture or product herein is H, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, selected from the group consisting of Cd, In, Sn, Sb, Te, I, Cs, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, lanthanoids and actinoids. may be free of any one of the chemical elements; However, any required chemical elements (eg, C and H required for polyolefins, or C, H and O required for alcohols) are not excluded.

Alternatively, separate embodiments are preceded. Aspect means an embodiment. ASTM means ASTM International, a standards organization located in West Konshohoken, Pennsylvania, USA. Any comparative examples are used for illustrative purposes only and are not prior art. Absence or absence means complete absence; Alternatively, it means undetectable. ISO is the International Organization for Standardization (Location: Chemin de Blandonnet 8, CP 401 - 1214 Vernier, Geneva, Switzerland). Terms used herein have their IUPAC meanings unless otherwise defined. See, eg, IUPAC, Compendium of Chemical Terminology. Gold Book, version 2.3.3, February 24, 2014]. IUPAC is the International Union of Pure and Applied Chemistry (IUPAC Secretariat, Research Triangle Park, North Carolina, USA). May is not a must, but rather grants an allowed choice. By operative is meant functionally possible or effective. Optionally (optionally) means absent (or excluded), alternatively present (or included). Properties can be measured using standard test methods and conditions. Ranges include endpoints, subranges, and integer and/or fractional values subsumed therein, provided that ranges of integers do not include fractional values.

Samples are prepared as test specimens, plaques, or sheets according to ASTM D4703-10, Standard Practice for Compression Molding Thermoplastics into Test Specimens, Plaques, or Sheets for Characterization.

Cell Stability Test Method: Pellets of polymer resin are melted at the melting temperature described below, Alpine 50 millimeters (mm) 25:1 length-to-diameter (L/D) dimension barrier single screw extruder, 120 mm inside without IBC (internal bubble cooling) Diameter dies are blown separately into films using a 1.2 mm die gap. The following properties of the 12.7 micrometer (μm) thick film were measured in an ASTM laboratory according to ASTM standards: (a) bubble rating at a standard print rate of 1.43 kilograms/hour=centimeter (kg/hour-cm, bubble grade STD); and (b) a bubble rating at a standard output speed with a maximum line speed greater than 76 or 106 meters/minute (m/min., bubble grade MLS250 or MLS350, respectively). The foam rating was scored on a scale of 1 to 5 as follows: 1. The film could not be manufactured. 2. The film could be made, but there was bubble instability in the production of the film. 3. The film could be made, but there was some bubble instability in the production of the film. 4. A film could be made with satisfactory cell stability. 5. The film could be made into a very stable bubble. If the cell rating is 3, 4 or 5, the resin passes the specific cell stability test. If the bubble grade is 1 or 2, the resin will not pass the specific bubble stability test. Since the MLS350 bubble rating is considered the most stringent bubble stability testing method compared to STD and MLS250, the MLS350 bubble grade is used herein as a basis for evaluating and improving methods for increasing bubble stability.

Complex Viscosity Test Method: 0.1 to 100 radians/s (rad/s) at 10% strain for a 25 mm diameter “puck” at 190° C. in an inert gas (N ₂ ) atmosphere using dynamic mechanical spectroscopy (DMS). ) to measure the complex viscosity, loss modulus, storage modulus, and phase angle through a frequency sweep. A convection oven is used to control the temperature. Pucks are prepared by compression molding pellets of test samples into 2 mm thick plaques and punched from 25 mm diameter “pucks”. Use an ARES-G2 or ARES-2 rheometer from TA Instruments equipped with upper and lower 25 mm parallel plates with an initial gap between them set to about 1.8 mm. Place the puck on the lower plate and allow the puck to reach thermal equilibrium. The gap is then closed and the puck is trimmed to remove excess material before measuring the complex viscosity. We obtain the values of the storage modulus (G'), loss modulus (G"), complex modulus (G*) and complex viscosity (η*) as a function of frequency (ω). At a given value of frequency (ω) we obtain the values of the complex viscosity ( Calculate η*) and obtain the SH1000 value by calculating the ratio of the two viscosities.For example, using the frequency (ω) values of 0.10 rad/s and 100 rad/s, the loss modulus of 3,000 Pascals (Pa) At a constant value of G" we get SH1000 = Eta*0.10/Eta*100 (i.e. η*(0.10 rad/s)/η*(100 rad/s)). SH1000 is the ratio of the two complex viscosities, Eta*0.10/ It is defined as Eta*100 (ie η*(0.10 rad/s)/η*(100 rad/s)).

Dart Drop Impact Test Method: Measured according to ASTM D1709-16a, Standard Test Method for Impact Resistance of Plastic Films by Free Fall Dart Test Method , Method A. Method A uses a dart with a hemispherical head of 38.10 ± 0.13 mm (1.500 ± 0.005 in) diameter that is dropped from a height of 0.66 ± 0.01 m (26.0 ± 0.4 in). This test method can be used for films having impact resistance that require a mass of from about 50 g or less to about 6 kg to rupture the film. Results are expressed in grams (g).

, 상기 식에서 M_w은 플로리 분포의 중량 평균 분자량이고; M은 특정 x축 분자량 점, (10 ^ [Log(M)])이며; dW_f는 플로리 분포의 모집단의 중량 분율 분포이다. Log(M), σ로 표현되는 너비의 정규 분포 함수에 따른 각 0.01 등간격 log(M) 지수에서 플로리 분포 중량 분율 dW_f; 및 Log(M), μ.

로 표현되는 현재 M 인덱스를 확장한다. 확산 함수가 적용되기 전과 후, Log(M)의 함수로서 분포 영역(dW_f /dLogM)은 1로 정규화된다. 각각 2개의 고유한 M_w 목표 값인 M_w-HMW 및 M_w-LMW와 각각 전체 성분 조성물인 A_HMW 및 A_LMW를 각각 갖는 HMW 공중합 성분 분획 및 LMW 공중합 성분 분획에 대한 2개의 중량 분율 분포 dW_f-HMW 및 dW_f-LMW를 표현한다. 두 분포 모두 독립적인 너비 σ(즉, σ _HMW = σ _LMW)로 확장되었다. 2개의 분포는 다음과 같이 합산되었으며:

, 상기 식에서 A_HMW + A_LMW = 1이다. 2차 다항식을 사용하여 501 log M 지수를 따라 측정된(통상적인 GPC로부터) GPC 분자량 분포의 중량 분율 결과를 보간한다. Microsoft Excel™ 2010 Solver를 사용하여 보간된 크로마토그래피로 결정된 분자량 분포와 각각의 성분 조성물 A_HMW 및 A_LMW으로 가중된 3개의 확장된 플로리 분포 성분(σ _HMW 및 σ _LMW) 사이의 501 LogM 지수의 등간격 범위에 대한 잔차 제곱의 합을 최소화한다. 성분에 대한 반복 시작 값은 다음과 같다: 성분 1: Mw = 30,000, σ = 0.300 및 A = 0.500; 및 성분 2: Mw = 250,000, σ = 0.300 및 A = 0.500. 성분 σ _HMW 및 σ _LMW에 대한 경계는 σ > 0.001가 되도록 제한되어 약 2.00의 M_w/M_n 및 σ < 0.500을 생성한다. 조성물 A는 0.000과 1.000 사이로 제한된다. M_w는 2,500과 2,000,000 사이로 제한된다. Excel Solver™의 "GRG 비선형" 엔진을 사용하고 정밀도를 0.00001로 설정하고 수렴을 0.0001로 설정한다. 수렴 후 해를 구한다(나타낸 모든 경우에서 해는 60회 반복 내에서 수렴됨).Deconvoluting test method: GPC chromatograms of bimodal polyethylene were divided into high molecular weight (HMW) component fractions and low molecular weight (LMW) component fractions using a Flory distribution extended to a normal distribution function as follows. match For the log M axis, set 501 equally spaced Log(M) indices divided by Log(M) 2 and Log(M) 7 at intervals of 0.01, which range represents molecular weights from 100 to 10,000,000 g per mole. log is a base 10 logarithmic function. For any given Log(M), the population of the Flory distribution is of the form:

, where M _w is the weight average molecular weight of the Flory distribution; M is the specific x-axis molecular weight point, (10 ^ [Log(M)]); dW _f is the distribution of the weight fraction of the population of the Flory distribution. Log(M), the Flory distribution weight fraction at each 0.01 equally spaced log(M) exponent according to the normal distribution function of width, expressed as σ, dW _f ; and Log(M), μ .

Extend the current M index expressed by . Before and after the spreading function is applied, the distribution area (dW _f /dLogM) as a function of Log(M) is normalized to 1. _{Two weight fraction distributions} , _{dW f -HMW} and dW represent _f-LMW . Both distributions were extended to an independent width σ (ie, σ _HMW = σ _LMW ). The two distributions were summed as follows:

, where A _HMW + A _LMW = 1. A quadratic polynomial is used to interpolate the weight fraction results of the GPC molecular weight distribution (from conventional GPC) measured along the 501 log M exponent. Equivalent of the 501 LogM exponent between the chromatographically determined molecular weight distribution interpolated using Microsoft Excel™ 2010 Solver and the three extended Flory distribution components ( σ _HMW and σ _LMW ) weighted by the respective component compositions A _HMW and A _LMW . Minimize the sum of squared residuals over the interval range. The iteration starting values for the components are: component 1: Mw = 30,000, σ = 0.300 and A = 0.500; and component 2: Mw = 250,000, σ = 0.300 and A = 0.500. Boundaries for components σ _HMW and σ _LMW are constrained to be σ > 0.001 resulting in M _w /M _n of about 2.00 and σ < 0.500. Composition A is limited to between 0.000 and 1.000. M _w is limited between 2,500 and 2,000,000. Use Excel Solver™'s "GRG Nonlinear" engine and set precision to 0.00001 and convergence to 0.0001. After convergence, a solution is found (in all cases shown, the solution converges within 60 iterations).

Density is ASTM D792-08, Standard Test Method for Density and Specific Gravity (Relative Density) of Plastics by Displacement , Measured according to method B (for testing solid plastics in liquids other than water, such as in liquid 2-propanol). Report results in grams/cubic centimeters (g/cm ³ ).

Elmendorf Tear Test Method: Measured according to ASTM D1922-09, Standard Test Method for Radio Tear Resistance of Plastic Films and Thin Sheets by Pendulum Method , Type B (Constant Radius). (Technically equivalent to ISO 6383-2) Report results as normalized tear in gram weight (gf) in transverse direction (CD) or machine direction (MD).

(EQ2); 방정식 3:

(EQ3); 및 방정식 4:

(EQ4). 샘플 실행 동안 공칭 유량 마커로서 데칸을 사용하여 시간 경과에 따른 유효 유량을 모니터링한다. 좁은 표준 보정 실행 동안에 얻은 공칭 데칸 유량으로부터 편차를 찾는다. 필요한 경우, 식 5에 따라 계산된 데칸의 공칭 유량의 ±2% 이내가 되도록 데칸의 유효 유량을 조정하며: 유량(유효) = 유량(공칭) * (RV_{(FM 계산됨)} / RV_{(FM 샘플)} (EQ5), 상기 식에서 유량(유효)은 데칸의 유효 유량이고, 유량(공칭)은 데칸의 공칭 유량이고, RV_{(FM 보정됨)}는 좁은 표준을 사용하여 컬럼 보정 실행을 위해 계산된 유량 마커 데칸의 보유 부피이고, RV_{(FM 샘플)}은 샘플 실행으로부터 계산된 유량 마커 데칸의 보유 부피이고, *는 수학적 곱셈을 나타내며, /는 수학적 나눗셈을 나타낸다. 데칸 유량 편차가 ±2% 초과인 샘플 실행으로부터 임의의 분자량 데이터를 폐기한다.Gel Permeation Chromatography (GPC) Test Method (Conventional GPC): A PolymerChar GPC-IR (Valencia, Spain) high temperature GPC chromatograph with an internal IR5 infrared detector (IR5, measuring channel) is used. The temperature of the autosampler oven compartment is set at 160°C and the temperature of the column compartment is set at 150°C. Using a column set of four Agilent "Mixed A" 30 cm 20 micron linear mixed bed columns; The solvent is 1,2,4 trichlorobenzene (TCB) containing 200 ppmw of butylated hydroxytoluene (BHT) sparged with nitrogen. The injection volume is 200 microliters. Set the flow rate to 1.0 milliliters/min. At least 20 narrow molecular weight distribution polystyrene (PS) standards (Agilent Technologies) arranged in a mixture of 6 "cocktails" with a separation of about 10 (decade) between individual molecular weights with molecular weights ranging from 580 to 8,400,000 in each vial (Agilent Technologies) Calibrate the column set. Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)] and using Equation 1 to convert the PS standard peak molecular weight to a polyethylene molecular weight: (M _polyethylene = A x (M _polystyrene ) ^B (EQ1), where M _polyethylene is is the molecular weight of polyethylene, M _polystyrene is the molecular weight of polystyrene, A = 0.4315, x represents the multiplication, and B = 1.0; where MPE = MPS x Q, where Q is measured independently by light scattering for absolute molecular weight It ranges from 0.39 to 0.44 to correct for column resolution and band broadening effects based on a linear homopolymer polyethylene molecular weight standard of about 120,000 and a polydispersity of about 3. Samples were soaked in TCB solvent at 160° C. for 2 hours under low-speed agitation. Dissolve at 2 mg/mL Generate a baseline subtracted infrared (IR) chromatogram at each equally spaced data collection point (i) and obtain the polyethylene equivalent molecular weight from the narrow standard calibration curve for each point (i) from EQ1. Number average molecular weight (M _n or M _n(GPC) ), weight average molecular weight (M _w or M _{w (GPC)} ) and z-average molecular weight (M _z or M _z(GPC) ) are calculated: Equation 2:

(EQ2); Equation 3:

(EQ3); and Equation 4:

(EQ4). During the sample run, the effective flow rate is monitored over time using the decane as a nominal flow rate marker. Find the deviation from the nominal decane flow rate obtained during the narrow standard calibration run. If necessary, adjust the effective flow rate of the decane to be within ±2% of the nominal flow rate of the decane calculated according to Equation 5: Flow(effective) = Flow(nominal) * (RV _{(FM calculated)} / RV _{(FM sample} ) ₎ (EQ5), where flow (effective) is the effective flow rate of decane, flow rate (nominal) is the nominal flow rate of decane, and RV _{(FM corrected)} is the calculated flow marker for the column calibration run using narrow standards. is the retention volume of decane, RV _{(FM sample)} is the retention volume of flow marker decane calculated from the sample run, * denotes mathematical multiplication, / denotes mathematical division.Sample run with decane flow rate deviation greater than ±2% Discard any molecular weight data from

Test Film Preparation Method: See Examples below. Prior to testing, the films were conditioned at 23° C.±2° C. and 50%±10% relative humidity for at least 40 hours (after film preparation).

High Load Melt Index (HLMI) I _21.6 Test Method: Use ASTM D1238-10, Standard Test Method for Melt Flow Rate of Thermoplastics by Extrusion Platometer, using the condition of 190°C/21.6 kilograms (kg). Results are reported in grams eluted per 10 minutes (g/10 min).

Melt Index ("I _5.0 ") Test Method: Measured for ethylenic (co)polymers according to ASTM D1238-13 using conditions of 190° C./5.0 kg.

Melt Flow Ratio MFR5: ("I _21.6 /I _5.0 ") Test Method: Calculated by dividing the value of the HLMI I _21.6 Test Method by the value of the Melt Index I _5.0 Test Method.

Melt Storage Modulus Test Method: For a polymer melt at 190°C, determine the value of G' (G″=3,000 Pa) in Pascals of the melt storage modulus (G') at a dynamic frequency where the loss modulus (G″) is equal to 3,000 Pa. At various frequencies from 0.01 radians/s (rad/s) to about 100 rad/s using dynamic mechanical spectroscopy (DMS) by ARES-G2 Advanced Rheometric Expansion System (TA Instruments) with parallel plate geometry to obtain small Strain (10%) oscillatory shear is performed.

Example

The required bimodal HDPE resins 1 to 4 are (0) from the previous resin prepared in-house by the previous set of polymerization (reactor) conditions in the previous run (1) to the first set of polymerization (reactor) conditions in run 1, ( were sequentially prepared in a single reactor by switching 2) run 2 to a second set of such conditions, (3) run 3 to a third set of such conditions, and (4) run 4 to a fourth set of such conditions. . Runs 1 to 4 include a reactor vessel containing a fluidized bed of powder of a bimodal polyethylene copolymer composition, and a lower head disposed above and defining a lower gas inlet to reduce the amount of resin fines that can escape from the fluidized bed. This was carried out in a pilot scale fluidized bed gas phase polymerization reactor (pilot reactor) comprising a distributor plate with an expanding section or cyclone system at the top of the reactor vessel. The expanded section defines a gas outlet. The pilot reactor has sufficient power to continuously cycle or loop gas from out of the gas outlet to the surroundings in the upper extended section of the reactor vessel down to or into the lower gas inlet of the pilot reactor and through the distributor plate and fluidized bed. It further includes a compressor blower. The pilot reactor further includes a cooling system to remove the heat of polymerization and maintain the fluidized bed at the target temperature. The composition of the gases fed into the pilot reactor, such as ethylene, hydrogen and 1-alkene, is monitored by an in-line gas chromatograph in a cycle loop to maintain specific concentrations that can define and control the polymer properties. The gas can be cooled so that its temperature can be lowered below its dew point, where the pilot reactor is in condensing mode operation (CMO) or induced condensing mode operation (ICMO). In CMO, the liquid resides downstream of the cooler and in the lower head below the distributor plate. The catalyst in each run was a silica-supported bimodal catalyst system containing a combination of bis(butylcyclopentadienyl)zirconium dimethyl and bis(2-(pentamethylphenylamido)ethyl)-amine zirconium dibenzyl, which The modal catalyst system is available as PRODIGY™ BMC-300 from Univation Technologies, LLC, a subsidiary of the Dow Chemical Company of Midland, Michigan. In each run 1-alkene was 1-butene and isopentane was 7 mol %. Polymerization/reactor conditions for Runs 1-4 are shown in Table 1 below.

Required bimodal HDPE resin 1: LMW poly(ethylene-1-butene) copolymer component with M _w of 15,160 g/mol and HMW poly(ethylene-1-butene) copolymer with M _w of 527,226 g/mol The required bimodal high density poly(ethylene-1-butene) copolymer resin having the constituents.

Required bimodal HDPE resin 2: LMW poly(ethylene-1-butene) copolymer component with M _w of 18,062 g/mol and HMW poly(ethylene-1-butene) copolymer with M _w of 583,069 g/mol The required bimodal high density poly(ethylene-1-butene) copolymer resin having the constituents.

Required bimodal HDPE resin 3: LMW poly(ethylene-1-butene) copolymer component with M _w of 19,0762 g/mol and HMW poly(ethylene-1-butene) with M _w of 579,035 g/mol The required bimodal high density poly(ethylene-1-butene) copolymer resin having a copolymer component.

Required bimodal HDPE resin 4: LMW poly(ethylene-1-butene) copolymer component with M _w of 28,067 g/mol and HMW poly(ethylene-1-butene) copolymer with M _w of 650,498 g/mol The required bimodal high density poly(ethylene-1-butene) copolymer resin having the constituents.

The required bimodal HDPE resins 1-4 have the properties shown in Table 2.

The following additives were added to the resin prior to oxygen tailoring the resin: the antioxidant pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propio obtained from BASF as IRGANOX 1010) 1000 ppm by weight nate, 200 ppm tris(2,4-di-tert-butylphenyl)phosphite obtained as IRGAFOS 168 from BASF, and 1000 ppm calcium stearate.

Oxygen-tailored bimodal HDPE resins 1A-1C were prepared by oxygen-tailoring the required bimodal HDPE resin 1 under various oxygen-tailoring conditions as shown in Table 3 below, and had the resin properties shown in Table 4 below.

Oxygen-tailored bimodal HDPE resins 2A-2C were prepared by oxygen-tailoring the required bimodal HDPE resin 2 under various oxygen-tailoring conditions as shown in Table 3 below, and have the resin properties shown in Table 5 below.

Oxygen-tailored bimodal HDPE resins 3A-3C were prepared by oxygen-tailoring the required bimodal HDPE resin 3 under various oxygen-tailoring conditions as shown in Table 3 below, and had the resin properties shown in Table 6 below.

Oxygen-tailored bimodal HDPE resins 4A-4B were prepared by oxygen-tailoring the required bimodal HDPE resin 4 under various oxygen-tailoring conditions as shown in Table 3 below, and had the resin properties shown in Table 7 below.

Oxygen-tailored bimodal HDPE resins 1A-1C, 2A-2C, 3A-3C, 4A and 4B were melted and an attempt was made to blow the melt into a film under film blowing conditions. Films were tested for cell stability as prepared according to the Cell Stability Test Method. The extruder conditions for each resin are shown in Table 3 below. All oxygen-tailored bimodal HDPE resins 1A-1C, 2A-2C, 3A-3C, 4A and 4B passed the STD cell stability test. Oxygen-tailored bimodal HDPE resins 1B, 1C, 2B, 2C, 3A to 3C, 4A and 4B passed the MLS250 bubble stability test and the oxygen-tailored bimodal HDPE resins 1A and 2A failed the MLS250 bubble stability test . The MLS350 bubble stability test results are later reported in Tables 4-7.

As shown in Tables 4-7, the comparative oxygen-tailored bimodal HDPE resins had a melt storage modulus G' (at G" = 3000 Pascals) in the inventive range of 1565 to 1900 Pascals and an inventive range of 38.0 to 50.0. They do not all have a complex viscosity ratio SH1000, and thus their comparative films fail the stringent MLS350 cell stability test.In advantageous contrast, the oxygen-tailored bimodal HDPE resin of the present invention has an inventive range of 1565 to 1900 Pascals. It had both a melt storage modulus G' (at G" = 3000 Pascals) and a complex viscosity ratio SH1000 in the inventive range of 38.0 to 50.0, so the inventive film passed the stringent MLS350 cell stability test. This method uses the advanced rheological properties of dynamic mechanical spectroscopy (DMS), but analyzes the data in other ways that are more sensitive to changes in resin composition and properties. Thus, the method of the present invention to increase the cell stability of the required bimodal HDPE resin requires that the resin's melt storage modulus G' (at G" = 3000 Pascals) and the complex viscosity ratio SH1000 be controlled simultaneously. It advantageously uses positive oxygen tailoring based on molecular weight distribution.This method results in a slight change (50% or less) in both the melt storage modulus of the resin, G' (at G″ = 3000 Pascals) and the complex viscosity ratio SH1000, Achieving the target increase in the MLS350 cell stability of the resin.

The results of the present method can be compared with the results of the prior methods. Conventional methods are not configured to increase the cell stability of the required bimodal HDPE resin. 1 is a copy of prior art FIG. 2 from Neubauer (US 2011/0178262 A1) and a first non-inventive method using only RSI values for an oxygen-tailored bimodal HDPE resin and melt elasticity (G at 0.1 rad/s); '/G") alone. Figure 2 shows the melt elasticity (G'/G" at 0.1 rad/s) and complex viscosity ratio for an oxygen-tailored bimodal HDPE resin. Shown are the results of a non-inventive third method using a combination of SH1000. 3 shows the molecular weight distribution for a bimodal HDPE resin requiring oxygen-tailoring, and the results of the method of the present invention using a combination of a melt storage modulus G' (at G" = 3000 Pascals) and a complex viscosity ratio SH1000. In Figure 3, oxygen-tailored bimodal HDPE resins 1B, 1C, 2B, 2C and 3C of the present invention are marked "Pass" and non-inventive oxygen-tailored bimodal HDPE resins 1A, 2A, 3A , 3B, 4A and 4B are marked as “fail.” Methods of the present invention rather than methods other than those of the present invention may be used for compositional changes.

The method of the present invention produced the oxygen-tailored bimodal HDPE resins 1B, 1C, 2B, 2C, and 3C of the present invention and films thereof. Films of the present invention have a dart drop impact of at least 260 grams (g) (e.g., 261 to 321 g), a machine direction (MD) Elmendorf of at least 23 grams (g) (e.g., 24-29 g). It has a beneficial combination of impact and tear properties, including tearing, and transverse direction (CD) Elmendorf tears of greater than 31 grams (g) (eg, 32-51 g). Dart drop impact and tear properties are measured by each of the test methods described above. Accordingly, the films of the present invention are useful for film applications such as packaging and medical applications.

Claims (11)

contains a higher molecular weight (HMW) polyethylene polymer component and a lower molecular weight (LMW) polyethylene polymer component and has an overall density of 0.935 to 0.970 grams per cubic centimeter (g/cm ³ ) and 200,000 to 450,000 grams per mole (g/mole). mol) of a required bimodal high density polyethylene (HDPE) resin having an overall weight average molecular weight (M _w ), wherein the required bimodal HDPE resin The properties of the bimodal HDPE resin differ from those of the previous resin prepared in the same reactor and the required bimodal HDPE resin has a first melt storage modulus G' (at loss modulus G″ = 3000 Pascals) of less than 1501 Pascals and a first between 33.0 and 49.0 Pascals. It requires increased cell stability because it has a complex viscosity ratio SH1000, wherein the method
contacting said melt of said desired bimodal HDPE resin under oxygen-tailoring conditions with an oxygen-tailoring mixture consisting essentially of a tailoring effective amount of molecular oxygen gas (O ₂ ) and at least one inert gas, wherein said melt during said contacting 235° C. to 251 to prepare an oxygen-tailored bimodal HDPE resin having a second melt storage modulus G′ (at G″=3000 Pascals) of 1565 to 1900 Pascals and a second complex viscosity ratio SH1000 of 38.0 to 50.0. at a temperature of °C;
The density is measured according to ASTM D792-13, Method B;
The M _w is determined according to the gel permeation chromatography (GPC) test method;
Each of the above melt storage modulus G' (at G″ = 3000 Pascals) is measured according to the Melt Storage Modulus Test Method;
Each of the complex viscosity ratios SH1000 is equal to Eta*0.10/Eta*100, where Eta*0.10 is the complex viscosity in Pascal-seconds (Pa-s) measured at 0.10 radians/second (rad/s) and Eta*100 is the complex viscosity in Pa-s measured at 100 rad/s, both determined according to the Dynamic Mechanical Analysis test method. The method of claim 1 , wherein the tailoring effective amount of O ₂ gas in the contacting step is as described by any one of limitations (i) to (ii): (i) X volume % (vol %) of the oxygen-tailoring mixture ) of O ₂ gas concentration; and (ii) the amount of O ₂ gas is parts by weight Y (ppmw) per million parts by weight of bimodal HDPE resin required. 3. The oxygen-tailoring mixture according to claim 1 or 2, wherein the oxygen-tailoring mixture has an O ₂ gas concentration of X volume % (vol%), and the oxygen-tailoring conditions meet any one of restrictions (i) to (iv). A method comprising: (i) the melt is at a temperature between 235°C and 245°C; (ii) the melt is at a temperature between 236° C. and 241° C.; (iii) the at least one inert gas of the oxygen-tailoring mixture is molecular nitrogen (N ₂ ), argon, helium, CO ₂ , one or more alkane(s), or a combination of any two or more thereof; and (iv) both (i) and (ii) and (iii). 4. The method according to any one of claims 1 to 3, wherein the oxygen-tailored bimodal HDPE resin has any one of limitations (i) to (iii): (i) a second melt storage modulus G '(at G" = 3000) is between 1565 and 1800 Pascals; (ii) the second complex viscosity ratio SH1000 is between 40 and 49.4; (iii) both (i) and (ii). 5. The method of any one of claims 1 to 4, wherein the oxygen-tailored bimodal HDPE resin passes the MLS350 Cell Stability Test determined according to the Cell Stability Test Method. Method according to any one of claims 1 to 5, wherein the required bimodal HDPE resin has any of the limitations (i) to (vi): (i) the overall density is 0.940 to 0.960 g/cm ³ Im; (ii) the total Mw is between 250,000 and 400,000 g/mol; (iii) the first melt storage modulus G' (at G" = 3000 Pascals) is 1001 to 1300 Pascals; (iv) the first complex viscosity ratio SH1000 is 35.0 to 48.0; (v) 8.0 to 10.0 grams/10 minutes an overall high load melt index (HLMI or I _21.6 ) of (g/10 min), and (vi) an overall melt flow ratio of 25 to 45 (MFR5 or I _21.6 /I _5.0 ), where I _21.6 is 190°C/ Measured according to ASTM D1238-13 using the condition of 21.6 kilograms (kg) I _5.0 is measured according to ASTM D1238-13 using the condition of 190°C/5.0 kg -. 7. The method according to any one of claims 1 to 6, further comprising the following preliminary steps (A) and (B) before the contacting step:
(A) determining the molecular weight distribution of the required bimodal HDPE resin, wherein the molecular weight distribution is (a1) the ratio of the weight average molecular weight of the HMW polyethylene polymer component to the weight average molecular weight of the LMW polyethylene polymer component (M _{w- HMW} /M _w-LMW );
(B) determining the effective tailoring amount of molecular oxygen gas (O ₂ ) effective in the contacting step as a function of the determined molecular weight distribution of the required bimodal HDPE resin. 8. The method according to claim 7, wherein the required bimodal HDPE resin has any of the limitations (i) to (iii): (i) the molecular weight distribution is (a1) the ratio M _w-HMW /M _w-LMW , wherein M _w-HMW /M _w-LMW is 23 to 45; (ii) the molecular weight distribution is (a2) the ratio of the number average molecular weight of the HMW polyethylene polymer component to the number average molecular weight of the LMW polyethylene polymer component (M _n-HMW /M _n-LMW ), where M _n-HMW /M _n-LMW is 18 to 30; (iii) the molecular weight distribution is (a3) the ratio of the z-average molecular weight of the HMW polyethylene polymer component to the z-average molecular weight of the LMW polyethylene polymer component (M _z-HMW /M _z-LMW ), where M _z-HMW /M _z-LMW is 18 to 45, wherein M _w , M _n and M _z are determined according to a gel permeation chromatography (GPC) test method. Oxygen-tailored bimodal HDPE resin prepared by the method of claim 1 . A blown film comprising the oxygen-tailored bimodal HDPE resin of claim 9 . contains a higher molecular weight (HMW) polyethylene polymer component and a lower molecular weight (LMW) polyethylene polymer component and has an overall density of 0.935 to 0.970 grams per cubic centimeter (g/cm ³ ) and 200,000 to 450,000 grams per mole (g/mole). A method for determining whether a bimodal high density polyethylene (HDPE) resin having an overall weight average molecular weight (M _w ) of measuring the modulus G″ = at 3000 Pascals) and the complex viscosity ratio (shear thinning) SH1000, and the bimodal HDPE resin has a melt storage modulus G′ (at loss modulus G″ = 3000 Pascals) of less than 1501 Pascals and has a complex viscosity determining that increased cell stability is required when the ratio (shear thinning) SH1000 is between 33.0 and 49.0.

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